This invention relates generally to improvements in the mounting of the large or main rear wheels for a wheelchair or the like. More particularly, this invention relates to an improved camber sleeve assembly for rotatably receiving and supporting the axles of the wheelchair wheels at a variably selected yet rigidly fixed camber angle.
Wheelchairs in general are relatively well-known in the art to include interconnected frame components having a seat structure mounted thereon, with the frame components being supported for rolling movement by relatively large rear wheels and comparatively smaller front wheels. In many such wheelchairs, various structural adjustment features are provided including, for example, seat position and/or height adjustment, armrest position, etc., to meet the needs of the individual using the wheelchair. In addition, some wheelchair designs incorporate means for adjusting the positions of the relatively large rear wheels, such as adjustment of the vertical height of the wheel axis, adjustment of the lateral position of the wheel axis with respect to the wheelchair seat structure, and/or adjustment of the rear wheel camber angle.
Typically, adjustment of the rear wheel camber angle has been accomplished by supporting a wheel axle within a bushing or sleeve which is mounted in turn onto a camber plate secured at a selected camber angle to the wheelchair frame. In accordance with one technique, as described in U.S. Pat. No. 4,477,098, washers or shims are used to mount the camber plate onto the wheelchair frame at the desired camber angle. In another approach, as described in U.S. Pat. No. 4,768,797, the camber plate includes multiple mounting holes oriented at different angles to achieve any one of several camber angle mounting positions. In either case, the camber angle is obtained by the particular mounting orientation of the camber plate relative to the wheelchair frame, such that removal and reinstallation of several bolts or screws are typically required in order to select and/or change the camber angle of each rear wheel. Moreover, the use of shims and the like to set the camber angle results in an assembled structure which often has inadequate rigidity and strength to withstand normal loads in a wheelchair environment.
Accordingly, there exists a significant need for improvements in devices for selecting and/or adjusting rear wheel camber angle in a wheelchair, particularly wherein the device is quickly and easily set to a selected position to provide rigid and durable wheel support at the selected camber angle. The present invention fulfills these needs and provides further related advantages.